Field of the Invention
The present invention relates to a honeycomb structure, and a manufacturing method of the honeycomb structure. More particularly, it relates to a honeycomb structure for use to purify an exhaust gas emitted from a diesel engine, and including a cordierite component which can be fired at a low temperature, and a manufacturing method of the honeycomb structure.
Description of the Related Art
Heretofore, a honeycomb structure made of ceramics (hereinafter simply referred to as “the honeycomb structure”) has broadly been used in a use application such as a car exhaust gas purifying catalyst carrier, a diesel particulate removing filter, or a heat reservoir for a burning device. The honeycomb structure is manufactured by preparing a forming material (a kneaded material), extruding the material into a desirable honeycomb shape by use of an extruder, and firing, at a high temperature, a honeycomb formed body obtained by performing raw-cutting, drying and end face finishing.
A diesel engine is operated in an excessive state of oxygen, and hence NOx cannot be reduced and treated by using a three-way catalyst for use in a usual gasoline engine. As a technology to reduce NOx in an atmosphere where oxygen is excessive, a selective catalytic reduction (SCR) technology is known. The selective catalytic reduction (SCR) has been developed as a technology of reducing NOx by use of ammonia as a reducing agent and purifying an exhaust gas from a stationary emission source such as a power station, and a titania-vanadia based catalyst is used.
In recent years, it has been required that NOx emitted from the diesel engine is purified at a high efficiency, and attempts have been made to apply the above technology concerned with the selective catalytic reduction to a diesel vehicle. For example, there has been developed a technology (see Patent Document 1) of loading a titania-vanadia based catalyst onto a honeycomb structure including a cordierite component (hereinafter referred to as “a cordierite honeycomb”) or a technology (see Patent Document 2) of forming the titania-vanadia based catalyst into a honeycomb shape.
The cordierite honeycomb has lattice-like partition walls defining a plurality of polygonal cells which extend from one end face to the other face and form through channels for a fluid. The cordierite component includes three components of silicon, aluminum and magnesium, and a material including the cordierite component has characteristics that its thermal expansion coefficient is low as compared with an alumina material or the like and that the material is excellent in thermal shock resistance and resisting strength. Therefore, the cordierite honeycomb has broadly been utilized in fields of the above car exhaust gas purifying catalyst carrier and the like.
[Patent Document 1] JP-B-H08-011194
[Patent Document 2] JP 2675321